Safety device for counterbalanced members



May 18, 1954 c. PAULSON 2,678,788

SAFETY DEVICE FOR COUNTERBALANCED MEMBERS Filed Oct. 8, 1952 j ii,

a 54 IA/VZ-"A/TOR ATTORNEY Patented May 18, 1954 SAFETY DEVICE FORCOUNTERBALANCED MEMBERS Christian Paulson,

Eimhurst, 111., assignor to Western Electric Company,

Incorporated, New

York, N. Y., a corporation of New York Application October 8, 1952,Serial No. 313,768

8 Claims.

This invention relates to a counterbalancing device for supporting apart in vertically adjusted positions and more particularly to a safetydevice associated with said movable part and said counterbalancingdevice for arresting the free falling movement of said part in the eventof failure of said counterbalancing device.

In various forms of apparatus where a movable part such as, for example,a glass bell jar is adjustably mounted for vertical movement andyieldably held in adjusted position by a counterbalancing device, itfrequently happens that as a result of prolonged use of the apparatus acomponent of the counterbalancing device breaks and the counterbalancingdevice loses its hold on the bell jar which falls and may injure theoperators hands and which frequently is darnaged as a result of thefall.

It is an object of the present invention to provide a safety device fora vertically movable counterbalanced part to retard or arrest the freefalling movement of the part in the event of failure of saidcounterbalancing device.

It is a further object of the invention to provide a mechanismapplicable to one of a pair of relatively movable parts and capable ofactuation to retard or arrest the relative movement of said members inone direction.

In accordance with one embodiment of the invention as applied to a belljar mounted on a :7

guide member slidable in a stationary tubular guide member for verticalmovement to and from upper and lower positions and having acounterbalancing device associated therewith for yieldably holding thebell jar in adjusted position, there is provided a helical springmounted on a reduced cylindrical portion of the movable guide formovement therewith within the tubular stationary guide member. Thehelical spring with its upper end secured to the movable guide, isstretched and maintained in axially expanded position with the other endthereof releasably interconnected through a pivoted lever on the movableguide to one end of a flexible tape of the counterbalancing device, thetape being operatively connected to the movable guide member by saidpivoted lever and also serving to retain said lever in operativeposition to hold said spring under tension in extended position. Uponfailure of the tape the pivoted lever is free to turn and the lower endof the spring is disengaged therefrom as the spring contracts towardsits upper end, causing the spring to increase slightly in diameter andgrip the inner surface of the stationary guide to arrest the movement ofthe movable guide and the bell jar.

Other objects and advantages of the invention will become apparent byreference to the following detailed description thereof and theaccompanying drawings illustrating a preferred embodiment, in which:

Fig. 1 is an elevational view of a welding fixture having a bell jarmovable thereon and a balancing device for supporting the bell jar invertically adjusted position and showing a safety device therefor;

Fig. 2 is a vertical sectional view through a portion of the movable andstationary guide members for the bell jar showing the members and thesafety device thereon in one position;

Fig. 3 is a view similar to Fig. 2 showing the parts in changedposition; and

Fig. i is a sectional view taken on the line 4-4 of Fig. 2.

In Fig. l of the drawings there is shown a welding fixture it having aglass bell jar H which is secured at its upper end as by brackets I l toa pair of movable tubular guide members i5 which are mounted for slidingmovement within a pair of stationary tubular guide mem bers H3. Thestationary guide members are interconnected by a pair of cross members[9 and 20, the latter of which rests on a bench top or table 2! forsupporting the welding fixture thereon. Supported 0n the upper crossframe member I9 is a plate 23 on which is mounted a holder 2&- for theparts to be brazed. The bell jar H is adapted to be moved to and from anupper open position in spaced relation to the plate 23 and a closedposition with the lower end thereof in engagement with the plate 23 andan inert gas is adapted to be flowed into the interior of the bell jarthrough a pipe 25 to provide an inert atmosphere around the parts beingbrazed during the brazing operation.

Counterbalancing means so are provided for resiliently supporting thebell jar in adjusted positions. As shown herein the counterbalancingmeans as are of a commercial type of window sash balance comprising acasing 31 enclosing a spiral spring 32, the inner end of which issecured to a pin 33 fixed in the casing and the other end of which isconnected to a flexible extensible element 34 in the form of anelongated metal ribbon or tape. A pair of counterbalancing devices aresecured to the stationary guide members 18 by collars 3i and screws 38engaging flanges 39 on the casing iii of the counterbalancing device.The tape is adapted to pass through an aperture in the stationary guidemember 18 and through an elongated slot in the movable guide member 15and extend downwardly within the tubular guide member for attachment tothe lower end thereof.

An apertured link secured to the lower end of the tape passes over andis connected to the arm i! of a connector element or lever 42 which ismounted for pivotal. movement intermediate its ends on a pivot pin 43secured in the lower end of the movable guide member E5. The spring 32of the counterbalancing device 3| is tensioned to move the tape upwardlyso that the tape urges the arm 3! upwardly into anotch 44 and intoengagement with the end of the movable guide member 55 to form aconnection between the flexible tape 35 and the movable guide member I5.

The lower portion at of the movable guide member i5, the outer diameterof which is slightly smaller than the inner diameter of the stationaryguide member 13, is reduced in. diameter to provide an annular space 47between the lower portion of the movable guide member and the innersurface of. the stationary guide member and to provide a shoulder 48 onthe movabl guide member defining the upper limit of the annular space.A- helical spring 50 is provided in the annular recess i? encircling theportion '45 of the movable guide and has its upper end inserted througha recess 52' in the wall of the guide [5 and is secured to the guide l5adjacent the shoulder 4d. The spring 50 which has a plurality ofconvolutions is stretched into an extended condition with the lower endthereof, which is formed into a hook 54'", looped over the end of thearm 55 of the lever 42. A slot 56 is provided in the lower end of themovable guide member If; for receiving the arm 55 therein to provideclearance for pivotal movement thereof. The spring 56, which, beforeapplication to the movable guide member I5, is wound with theconvolutions thereof positioned close to each other, is so proportionedthat in its contracted position (Fig. 3) the spring grippingly engagesthe inner surface of the stationary guide tube It, and in its axiallyexpanded position (Fig. 2) the outside diameter of the spring is reducedto provide clearance between the spring and the stationary guide memberpermitting free movement of the spring and the movable guid memberwithin the stationary guide-member. In its axially expanded position thespring Silmaygrippingiy engage the movable guide-member l5.

In the event that the-flexible tape 34 or other components of thecounterbalancing device 30 should break or fail, the helical spring 50wou1d be moved from its axially expanded position (Fig. 2) into itscontracted position (Fig. 3) causing the diameter of the spring toenlarge slightly and causing the outer surface thereof to move intofrictional gripping engagement with the inner surface of the stationaryguide member IE to arrest the downward movement of the movable guidemember and the bell jar supported thereon. Thus, the spring 53' acts asa safety member for arresting the downward falling movement of the belljar H in the event of failure of the flexible tape 34 or other parts ofthe counterbalancing device.

It is to be understood that the above-described arrangements are simplyillustrative of the application of the principles of this invention.Numerous other arrangements may be readily devised by those skilled inthe art which will embody the principles of the invention and fallwithin the spirit and scope thereof.

What is claimed is:

l. A safety stop for interconnecting an article and its counterbalanceand operable to hold the article upon failure of the counterbalancecomprising inner and outer telescoping tubular elements, a coil springfixed to and encircling a portion of the inner tubular element andbiased to bear against the outer tubular element for preventing relativemovement between said tubular elements, said spring being movable to anaxially expanded position to permit relative movement between saidtubular elements, a lever pivoted intermediate its ends on the innertubular member and having one end releasably connected to said springfor holding said spring in axially expanded position, meansinterconnecting the other end of the lever with the counterbalance, andmeans interconnecting the inner tubular element with the article.

2. In a device of the type described, the combination of a stationaryguide member having a cylindrical inner surface; a movable guid memberslidable within said stationary member for supporting an article formovement through a substantially vertical path, a counterbalancingdevice on said stationary member having an element stressed for movementupwardly for yield-- ably supporting said movable member in adjustedposition, a helical spring within said stationary guide member havingone end thereof secured to said movable guide member for movementtherewith and having a normal contractedposition with the outer surfacethereof in gripping. engagement with saidcylindrical surface to preventrelative movement of said members in one direction, said helical springhaving its other end axially movable away from said One end to axiallyexpand and radially contract said spring to provide clearance betweensaid spring and said cylindrical surface, means for interconnecting saidelement of said-counterbalancing device and the other end ofsaiclihelical spring for yieldably holding said spring in axiallyextended position and for eifecting a connection of said element to.said movable guide member.

3. In a device of the. type described, the combination of an outervertically disposed stationary tubular member, an: inner movable tubularmem ber mounted in telescoping relation to said outer member for axialmovement for. supporting a part. for verticalmovement and having areduced portion in spaced relation to the inner surface of said outertubular member to provide an annular space between. said reduced portionof the inner tubular member and said outer tubular member and to form ashoulder on the. inner tubular member, a helical sprin encircling saidreduced portion of said inner tubular member and having one end thereofattached thereto adjacent said shoulder, said spring having a normalcontracted position with the convolutions thereof in close proximity toeach other and with the outer surfaces thereof in gripping engagementwith. the inner surface of said outer tubular member to prevent relativemovement between the outer tubular member and the spring and the innertubular member, a counterbalancing device having an element extendinginto said inner tubular member and stressed. for movement upwardly toyieldably support the movable tubular member and the part attachedthereto in adjusted position, means for mounting said counterbalancedevice in fixed relation to said stationary tubular member, and meansincluding a member pivotally mounted on said inner tubular member forinterconnecting the flexible element of said counterbalancing device andthe other end of said helical spring for yieldably holding said springin axially extended position and for effecting a connection of saidflexible member to said inner tubular member.

4. The combination with a part to be supported in vertically adjustedpositions of a counterbalance for retaining the part in said positions,and means for interconnecting the article and counterbalance comprisinga stationary tubular guide member having a cylindrical inner surface, amovable member slidable within said. stationary member for supportingsaid part for vertical movement, said counterbalance being mounted onsaid stationary member and having an extensible element stressed formovement to yieldably support said movable member in adjusted position,a helical spring Within said stationary guide member having one endthereof secured to said movable guide member for movement therewith andhaving a normal axially contracted position with the outer surfacethereof in gripping engagement with said cylindrical surface to preventmovement of said movable guide member in one direction, said helicalspring having its other end axially movable away from said one end toaxially expand and radially contract said spring to provide clearancebetween said spring and said cylindrical surface, and a connector memberpivotally mounted on said movable guide member for movement portionthereof engageable with said extensible element and being stressedthereby. to an operative position for effecting a connection betweensaid extensible element and said movable member, said connector memberhaving a portion engageable with the other end of said helical springfor yieldably holding said spring in axially extended position when saidconnector member is in said operative position, said connector memberbeing movable from said operative position to release said spring inresponse to failure of said extensible element to retain said connectormember in operative position.

5. In a device of the type described, the combination of a stationarytubular guide member having a cylindrical inner surface, a movabletubular guide member slidable within said stationary member forsupporting an article for vertical movement, a counterbalancing deviceon said staionary member having an extensible element stressed formovement upwardly to yieldably support said movable member in adjustedposition, said movable member having a shoulder thereon and a portion ofreduced diameter extending bulow said shoulder, a helical springencircling said reduced portion of the movable guide member and havingone end thereof secured to said movable member adjacent the shoulderthereon for movement therewith and having a normal contracted positionwith the outer surface thereof in gripping engagement with saidcylindrical surface to prevent movement of said movable guide member inone direction, said helical spring having its other end axially movableaway from therewith and having a said one end to axially expand andradially con- 55 tract said spring to provide clearance between saidspring and said cylindrical surface, and a lever pivotally mountedintermediate its ends on rippin said movable guide member and having aportion thereof engageable with said extensible member and movablethereby to an operative position with a portion of the lever inengagement with said movable guide member for connecting said element tosaid movable guide member, said lever having another portion forengaging said other end of the helical spring for yieldably retainingsaid spring in axially expanded position, said lever being movable fromsaid operative position to release said spring in response to failure ofsaid extensible element to retain said lever in operative position.

6. The combination with a first member having a cylindrical guideway anda second member movable therein of a helical spring attached to saidsecond member for movement therewith and movable to and from an axiallycontracted position with the spring in gripping engagement with thecylindrical guideway to prevent relative movement of said members in onedirection and an axially expanded position with the spring in spaced anddisengaged relation to said guideway to permit relative movement of saidmembers in either direction, and means for releasably maintaining saidspring in axially expanded position.

7. The combination of a pair of relatively movable telescoping tubular 1,embers having portions thereof in spaced relation to each other toprovide an annular space therebetween, a helical spring disposed in saidannular space, means for attaching said spring to one of said tubularmembers, said spring being movable to and from an axially contractedposition with the spring in engagement with the outer tubular member andin spaced relation to said inner tubular member and an axially expandedposition with the spring in spaced relation to said outer tubular memberand in gripping engagement with said inner tubular member, and means forreleaseably maintaining said spring in said. axially expanded position.

8. In a device of the type described, the combination of a first guidemember and a second guide member telescopingly disposed for movementrelative to each other, said first guide member having an innercylindrical surface encircling said second member, a helical springwithin said cylindrical surface having one end thereof secured to saidsecond member and having a normal contracted position with the outersurface thereof in gripping engagement with said cylindrical surface toprevent relative movement of said members in one direction, said springhaving its other end axially movable away from said one end tolongitudinally expand and radially contract said spring to provideclearance and freedom of relative movement between said spring and theinner surface of said first member, and means for releaseably holdingsaid spring in said longitudinally expanded position.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,229,976 Klais June 12, 1917 1,764,678 Fox June 17, 1930

